Radial arm saw

ABSTRACT

A radial arm assembly for mounting a power saw, the assembly comprising: a horizontally disposed base frame; two vertically oriented mounting posts disposed at opposite sides of an edge of the base frame; a cross-bar horizontally mounted on the posts at opposite ends of the cross-bar; an arm for supporting the saw, the arm being attached to the cross-bar substantially centered between the ends, the arm adapted to rotate over the base frame about a vertical axis, the arm comprising a guideway along substantially all of the arm; and, the saw being mounted on the arm and adapted to translate along the guideway, a blade of the saw being moveable with the saw along said guideway, unobstructed by either of the posts, and to and from a position substantially beneath the vertical axis, whereby cuts substantially corresponding to the full length of the arm may be effected.

BACKGROUND OF THE INVENTION

This invention seeks to improve on the current radial arm saws now onthe market. The standard radial arm saw has a cross cut capacity that islimited by the length of the arm. In order to cross cut 24" (1/2 thewidth of a 4'×8' panel) the arm has to be quite a bit longer than the24" travel of the roller head in the arm track. The roller head cannotbe retracted the full length of the arm. About 6" to 8" of the arm isused to support itself on the top of the post-base structure at the rearof the arm. The roller head strikes the post preventing it fromretracting to the entire length of the arm. On the current saws, inorder to let the operator cut 24" in one pull, the length of the armmust be increased by 6" to 8". With this extra length arm the rest ofthe saw must also be increased in size and weight. Because the arm mustbe longer, it too must be of heavier construction. To support thisheavier arm the post and base structure must be increased in size andweight. Because the arm is longer and heavier, the width of the tableand frame must be wider. For this reason current radial arm saws thatwill cut 24" in one pull are very large and heavy. They are made forheavy duty industrial use only. Smaller saws, having 10" to 12" blades,used by small shops and homecraftsmen, do not have this capacity at thepresent time. There is a great need for a smaller medium duty radial armsaw that will cut 24" and not be large, heavy and expensive.

The present radial arm saws that use only one post and base have adisadvantage when the saw is mitered to cross cut an angle other than90° to the fence. This is because the saw blade, in the retractposition, is located to the left of the pivot of the arm. When miteringto the right (45°) the blade is so far to the right that even theoriginal 90° cross cut must be located to the left of center on the worktable. This puts the right hand 45° miter on the table but positions theleft hand 45° miter off the table on the left side. When cutting a lefthand 45° miter on the current saws, the operator must move the fencefrom its normal position usually at least one-third of the weight towardthe front, to the extreme back position. On current radial arm saws, thesaw blade strikes the fence when mitering 45° to the right. If the sawblade is engaged to the back boards, as it must be, the saw cannot bemoved to the miter position unless the blade is raised first and thenlowered once it is in the desired miter position. On standard radial armsaws, on the market today, the location of the 90° cross cut being offcenter causes problems when cutting long boards.

Standard radial arm saws that use only one post and base combinationhave a very serious problem with alignment. They must be constructed sothat the post can go up and down in the base and, at the same time, notbe able to rotate in it at will. Any rotation, even the slightest, willcause the arm to deviate from its locked located position on the post.This can cause inaccurate angle cuts as well as waste of material andfrustration of the operator. The standard method of rotation preventionis the use of a key and key-way on the post - base combination. The basemust also have some method to take up for any wear between the base andthe post. A slight amount of play between the base and post can cause"end play" resulting in inaccurate cross cuts as well as misalignment ofthe blade to the fence when ripping (making cuts parallel to the fence).On present radial arm saws, the most difficult maintenance chore isconstant adjustment to eliminate "end play."

SUMMARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a radial armsaw that can cut up and behind the saw's mounting posts unobstructed bythese posts.

It is a further object of the invention to provide a radial arm saw thatmaintains accuracy of alignment by minimizing wear between post andbase, and the arm and the arm's supporting structure.

It is another object of the invention to provide a radial arm saw thatcan make left and right hand miter cuts substantially centered, left toright, on the table by pivoting the blade on its vertical centerline.

It is yet another object of the invention to substantially eliminate thenecessity for the operator to repeatedly raise and lower the saw bladeover the fence during miter cuts.

In accordance with these and other objects that shall become apparenthereinafter, there is provided a radial arm saw and support structuretherefore that overcomes the deficiencies of the prior art and securesthe objects of this invention by providing a support structure having ahorizontally disposed base frame and a pair of posts vertically mountedon the frame. Between the posts is a horizontal cross-beam rigidly fixedat its extremities across the tops of the posts. Mounted centrally onthe cross-beam is a combination support and bearing structure (which canbe a simple cylinder) upon which is mounted on elongate offset arm thatholds the saw. The arm is provided with a guideway along its length toguide the saw during cutting operations. The arm can rotate in ahorizontal plane about the support and bearing structure so as toposition the saw in any of a plurality of horizontal cutting directions.The posts are formed of telescoping members so as to enable one to raiseor lower the height of the cross-beam (and hence the saw).

By centrally mounting the arm between two posts, neither post obstructsmotion of the saw along the guideway, thus enabling the saw to movefreely beyond the fence during cutting operations. Because the heightadjustments and rotational arm adjustments are performed by distinctmembers, wear on each and consequent inaccuracy in alignment, isreduced.

As a further consequence of the scheme wherein there are no mounts postswhich can obstruct movement of the saw along the arm, an operator canslide the saw all of the way to the back of the arm while making cuts,that is, to a position between the posts. It is therefore possible tomake longer cuts. With this arrangement, miter cuts intersect oneanother at the same point along the guide fence, which is disposed atthe rear edge of the base or table. This make it unnecessary toconstantly re-align boards along the fence between such cuts.

The instant invention will be more fully understood from the followingdetailed description, it being understood, however, that the inventionis capable of extended application, and is not confined to the precisedisclosure. Changes and modifications may be made that do not affect thespirit of the invention, nor exceed the scope thereof, as expressed inthe appended claims. Accordingly, the instant invention will now bedescribed with particular reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the invention mounted on a frame.

FIG. 2 is a front elevational view of the invention, mounted on a frame,partially broken away.

FIG. 3 is a top plan view of the radial saw's arm.

FIG. 4 is a side elevational view of the arm along lines 4--4 of FIG. 3.

FIG. 5 is a side perspective view of the arm along lines 5--5 of FIG. 3.

FIG. 6 is a perspective view of miter locking ring, about which the armrotates.

FIG. 7 is a top plan view of the cross-beam.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With particular reference to the drawings, the following parts of theinvention are designated by reference numerals:

1 - Elevating Crank Handle: Can be mounted on right or left side. Also,can be located at table level. Any standard elevating method or locationof same can be used. Crank handle is secured to tie rod #3 and supportedby tie rod brackets 4.

2 - Worm and Gear: or the use of standard miter gears to cause elevatingscrew 29 to rotate when elevating crank handle 1 is turned.

3 - Tie Rod: assures that worm and gears 2 (or miter gears) will rotateat the same time and at the same speed. This action causes cross beam 5to raise and/or lower and remain parallel to the frame 28 and table 26.

4 - Tie Rod Brackets: mounted on posts 9 (or cross beam 5) to assure theengagement of worm and gear 2 (or miter gears).

5 - Cross Beam: Supported on posts 9 and holding arm post 6.

6 - Arm Post: secured to cross beam 5 via any standard method withenough play in elongated mounting hole 12b so slight rotation can beachieved before locking it securely to cross beam 5 via wrap aroundbolts 5a.

7 - Cross Beam Secure Bolts: To lock cross beam 5 to posts 9. Anystandard method of securing cross beam 5 to posts 9 can be used such assplitcasting on ends of cross beam 5 and wrap around bolts 5a.

8 - Safety Bolt: goes through casting of cross beam 5 and arm post 6.Safety bolt 8 goes through elongated hole 12b in arm post 6 enabling itto rotate a small amount in order to perform a rough alignment of arm 11to fence 25.

9 - Post: Two are used and they are engaged to base(s) 10. Posts are thesupport system to suspend cross beam 5. When elevating screw 29 isrotated via linkage to elevating crank handle 1 the two posts 9 willraise and/or lower due to their engagement to elevating nut 30.

10 - Base: Two are used to hold posts 9. The two base(s) 10 are mountedand secured to frame 26 using any standard method. Elevating nut(s) 30are secured to base 10 with any standard method.

11 - Arm: Cast iron or any other material used on standard radial armsaws. The arm 11 is mounted on the arm post 6 by split ring 11a and issupported by miter locator ring 12. This ring is secured to the bottomof the arm post 6 via any standard method such as pins, welding threads,etc. The arm 11 can swing to the right or left. Its limit is determinedby the spread of the post(s) 9 and base(s) 10. To increase the amount ofrotation of the radial arm (its extreme miter angle right and left), thedistance can be increased by locating the post 9 and base 10 far enoughapart so that the distance from the center of the cross beam 5 and theright and left post 9 - base 10 is longer than the arm 11. Naturally,the length of the cross beam 5 and table 26 - frame 28 would have to beincreased accordingly. The arm 11 has two tracks as used in any standardradial arm saw arm. These tracks are engaged to standard roller headbearings mounted on any standard type roller head 15. The arm also holdsa spring loaded pin that will locate into pre-cut (or cast) grooves onthe miter locator ring 12. The arm is equipped with any standard methodof securing the arm 11 to the arm post 6. Endcaps 18 are attached to theends of the arm 11 via any standard method such as screws. This enablesthe operator to remove and replace the roller head 15 as well as theentire motor assembly 17, 20, 21, 22, 19, 23. When the angle of miter isselected and the arm 11 is located at the angle, the arm is equippedwith standard locking methods to secure the arm 11 tight against (to)the arm post 6.

12 - Miter Locator Ring: is a pregrooved metal ring securely attached tothe arm post 6. The grooves on the miter locator ring 12 receive miterlocator pin 13 or any standard method of locating the miter angle of thearm 11.

13 - Miter Locator Pin: Or any standard method of radial arm saw miterlocation. This locator can be spring loaded and or a tapered lever type.Levers 33 and 33a which retract and engage the pin

can be used to eliminate the need for the operator to reach back to thearm post 6.

14 - Yoke Locator Pin: enables the operator to convert the saw fromcross cut to rip. This is the standard method of swinging the yokeassembly 17 in an out-rip or in-rip position. Yoke lock lever 16 is usedto secure the yoke 17 securely to the roller head 15.

15 - Roller Head: Standard method of enabling the operator to pull theentire assembly back and forth on the arm 11.

16 - Yoke Lock Lever: standard method of locking yoke 17 to roller head15.

17 - Yoke: standard method to hold motor 22 suspended above table 26.

18 - End Cap: attached to rear end of arm 11 to prevent roller head 15from going off the track in arm 11.

19 - Guard: standard radial arm saw guard attached to motor 22 to coversaw blade 24.

20 - Bevel Lock Lever: standard method to lock motor 22 to yoke 17 inorder to tilt the saw blade 24 to desired angle.

21 - Bevel Locator Pin: standard method to locate the tilt of the sawblade 24 at the popular important angles such as 90°, 45°, 30°, 0°.

22 - Motor: any standard radial arm saw motor can be used. Theconfiguration of the arm 11 is so designed that saw blade 24 will belocated down the center line of the arm post 6.

23 - Blade Washers: used to hold saw blade 24 will be located down thecenter line of the arm post 6.

24 - Saw Blade

25 - Fence: mounted on table 26 and back against base 10.

26 - Saw Table: mounted on frame 28 with table trunions 27.

27 - Table Trunions: used to hold table 26 to frame 28. Elongated holeson trunions 27 enable table 26 to be adjusted to make the table 26parallel to the arm 11 to ensure equal depth of cut by saw blade 24. Or,any other standard method of table adjustment.

28 - Frame: used to hold table 28 and base(s) 10. Legs can be attachedto underside of frame 28 to bring up table 26 to convenient workingheight.

29 - Elevating Screw

30 - Elevating Nut

In practice, the height of the saw is selected by cranking worm gears 2,and screw 29 and nut 30, thus lowering or raising cross beam 5. Tie rod3 between worm gears 2 enables the saw's operator to raise both posts 9in one operation, and ensures that each elevating screw 29 moves anidentical amount, keeping level cross beam 5.

In contradistinction to the prior art, these posts must undergo onlylinear displacement, i.e. move up and down; the cross frame, not theposts, support the rotational motion of the arm. Because of thisdifference the instant invention is not subject to the sort of wear thatis common in single post radial arm saws, which causes great difficultyin aligning such prior art saws for precise cuts. The saw assembly 17,19, 22, 24 can be rotated about locator ring 12 to the correcthorizontal (miter-cut, or cross-cut) position. As best seen in FIG. 2,if the saw assembly is drawn along arm 11 as far as possible towardsposts 9, the assembly would locate between posts 9, and blade 24 wouldlocate directly under ring 12. In the preferred embodiment, ring 12'saxis of symmetry would pass through the arbor of motor 22, and wouldbisect blade 24. Because of this alignment, when the saw rotates aboutring 12, the face of saw blade 24 rotates such that one point 24' on theblade's periphery always remains fixed with respect to the table. If onewere to make several miter cuts, it is at point 24' that these cutswould intersect (unlike the prior art, in which there is no such pointof intersection unless the operator were to move the wood along fence 25a distance necesary to make these cuts intersect). The bottom portion ofring 12 is notched to enable one to rotate the saw assembly into any ofseveral preselected miter positions. Pin 13 locks the saw assembly intothe preselected position.

After selecting the desired miter position, the saw assembly can bemoved along the length of arm 18 to make the desired cut.

Yoke 17 can rotate about a vertical axis, enabling one to make cutsparallel to fence 25. Yoke lever 16 is used to lock and unlock yoke 17against such rotation.

Motor 22 depends from yoke 17 via fork bracket 31, within which motor 22can pivot about a horizontal axis to allow for bevel cuts. Pin 21 locksand unlocks the motor from such pivoting.

The cross-beam of FIG. 7 is made from a single casting, and hasapertures 5b therein selected to yield a lightweight, and structurallystrong beam.

The instant invention has been shown and described herein in what isconsidered to be the most practical and preferred embodiment. It isrecognized, however, that departures may be made therefrom within thescope of the invention, and that obvious modifications may occur to aperson skilled in the art. Accordingly, the scope of the invention isdefined by, and to be determined solely by reference to the appendedclaims.

What I claim is:
 1. A radial arm assembly for mounting a power saw, saidassembly comprising:a horizontally disposed base frame; two verticallyadjustable mounting posts disposed at opposite sides of an edge of saidbase frame; means for precisely coordinating adjustment of said verticalposts; a cross-bar means horizontally mounted on said posts at oppositeends of said cross-bar means; an arm means for supporting said saw, saidarm means being rotatably attached to said cross-bar means about avertical axis between said ends, said arm means being thereby adapted torotate over said base frame about said vertical axis, said arm meanscomprising a guideway along substantially all of said arm; and, said sawbeing mountable on said arm means and adapted to translate along saidguideway, a blade of said saw being moveable with said saw along saidguideway, unobstructed by either of said posts, to and from a positionsubstantially intersecting said vertical axis, whereby vertical androtational adjustments of said saw are independent of one another andcuts substantially corresponding to the full length of said arm meansmay be effected.
 2. The radial arm assembly of claim 1, furthercomprising means for mounting a circular power saw to said arm means,said circular power saw having a circular saw blade disposed forrotation in a vertical plane, about a horizontal axis, said planepassing through said vertical axis.
 3. The radial arm assembly of claim2, further comprising a fence for guiding and positioning work pieces,said fence being disposed at said edge of said base frame adjacent saidmounting posts.
 4. The radial arm assembly of claim 3, wherein each ofsaid mounting posts comprises telescopic members operable in response tosaid coordinating adjustment means, for effecting said verticaladjustment.
 5. The radial arm assembly of claim 4, further comprisingmeans for precisely positioning said arm means at at plurality ofrotational positions about said vertical axis, whereby a plurality ofpremeasured miter angles may be selected.
 6. The radial arm assembly ofclaim 5, wherein said arm means is mounted to said cross-bar means at apoint laterally offset from said arm means at one end of said arm means.7. The radial arm assembly of claim 5, wherein said vertical axis isdisposed substantially centered between said ends.
 8. The radial armassembly of claim 1, further comprising a fence for guiding andpositioning work pieces, said fence being disposed at said edge of saidbase frame adjacent said mounting posts.
 9. The radial arm assembly ofclaim 1, wherein each of said mounting posts comprises telescopicmembers operable in response to said coordinating adjustment means, foreffecting said vertical adjustment.
 10. The radial arm assembly of claim1, further comprising means for precisely positioning said arm means atat plurality of rotational positions about said vertical axis, whereby aplurality of premeasured miter angles may be selected.
 11. The radialarm assembly of claim 1, wherein said arm means is mounted to saidcross-bar means as a point laterally offset from said arm means at oneend of said arm means.
 12. The radial arm assembly of claim 1, whereinsaid vertical axis is disposed substantially centered between said ends.13. A radial arm saw, comprising:a horizontally disposed base frame; twovertically adjustable mounting posts disposed at opposite sides of anedge of said base frame; means for precisely coordinating adjustment ofsaid vertical posts; a cross-bar horizontally mounted on said posts atopposite ends of said cross-bar; a circular power saw; a radial arm forsupporting said saw, said arm being rotatably attached to said cross-barabout a vertical axis between said ends, said arm being thereby adaptedto rotate over said base frame about said vertical axis, said armcomprising a guideway along substantially all of said arm, said sawbeing slidably mountable on said arm and adapted to translate along saidguideway, unobstructed by either of said posts, to and from a positionsubstantially intersecting said vertical axis, whereby vertical androtational adjustments of said saw are independent of one another andcuts substantially corresponding to the full length of said arm meansmay be effected.
 14. The radial arm saw of claim 13, wherein said sawhas a circular saw blade disposed for rotation in a vertical plane, saidplane passing through said vertical axis.
 15. The radial arm assembly ofclaim 13, wherein said arm is mounted to said cross-bar at a pointlaterally offset from said arm at one end of said arm.
 16. The radialarm assembly of claim 14, wherein said arm is mounted to said cross-barat a point laterally offset from said arm at one end of said arm.